Heightened blood pressure among key health concerns of a high-fat diet, study finds

08 Jan 2019 --- Heightened blood pressure is among the health concerns that following a high-fat diet presents to both genders, a new US rat study suggests. While the team hypothesized that high-fat fare would be harder on males, they found that in just four weeks, both young male and female rats experienced comparable increases in blood pressure. The researchers note the importance in understanding what we are eating, and how “consistently bad the high-fat diet may be for us.”

Published in the American Journal of Physiology, Heart and Circulatory Physiology, the study looked simultaneously at young males and female salt-sensitive rats, bred to become hypertensive in response to a high-salt diet. More recently, male rats have been shown to also have significant blood pressure response to a high-fat diet.

“Since women are more likely to be obese than men and the association between increases in body weight and blood pressure is stronger in women, we wanted to see if the same response occurs in the female as well,” says Dr. Jennifer C. Sullivan, Pharmacologist and Physiologist in the Department of Physiology at the Medical College of Georgia at Augusta University.

About one in three adults in the US is hypertensive, according to the Centers for Disease Control and Prevention, and about two-thirds of cases are associated with excessive weight gain.

The prevalence of metabolic syndrome – a cluster of cardiovascular risks that include higher blood pressure, blood sugar and cholesterol levels and more fat particularly around the waist – is higher in females than males, 34.4 percent compared with 29 percent, respectively, according to the American Heart Association and the National Health and Nutrition Examination Survey.

What did the study find?
They found the usual cardiovascular protection afforded to younger females appeared lost in the face of high-fat consumption. While the young male rats, like male humans, started with higher blood pressure than their female counterparts, both sexes rapidly experienced a comparable degree of blood pressure increase.

“You put them on high salt, and the males have a bigger increase in pressure; you put them on fat, and males and females have the same increase in pressure,” Sullivan says.

In both sexes, the high-fat diet also increased inflammation-promoting T cells and decreased the number of inflammation-dampening regulatory T cells, or Tregs, in the aorta, the biggest blood vessel in the body which they studied as an example of what was happening inside blood vessels.

In the kidneys, which play a major role in regulating blood pressure, they again found increases in inflammation-promoting T cells in both sexes but a greater increase in males.

Sullivan reiterates that the changes – in males and females alike – were independent of a significant weight gain and occurred in just four weeks.

“It really highlights the importance of understanding what you are eating,” says Sullivan. “I think we may be underestimating how bad a consistently high-fat diet is for us.”

gh-fat diet, both sexes actually ate less, which meant their caloric intake did not really increase. Still, males started out weighing more and continued to weigh more throughout the four weeks, although weight increases compared to rats on a normal diet were minimal.

Sullivan and her team are now directly addressing the hypothesis that T cells contribute to blood pressure increases on a high-fat diet, and whether that diet is directly driving an immune response that drives the blood pressure. She suspects it's the changes to fat cells driving it rather than a direct interaction between high-fat food and the immune response.

Diet has proven to be essential to maintaining overall health, as well as cardiovascular strength. A recent study by the American Heart Association (AHA) found that a vegan diet is more effective in reducing the risk of coronary heart disease than the AHA recommended diet. Patients suffering from heart disease may benefit from a plant-based, vegan diet as it reduces the high‐sensitivity C‐reactive protein – a key player in the development of major adverse cardiovascular events – though it does not help with weight loss, glycemic control or dyslipidemia more than the AHA recommended diet, according to the study.